Surge arresters of the type containing zinc oxide varistors and series gaps within an insulating housing or closure are currently available for mounting both in the vicinity of distribution transformers to protect the distribution transformers from voltage surges, and on riser poles in the vicinity of underground electrical substations, to protect the substation equipment from voltage surges.
Since zinc oxide varistors are currently being used in place of silicon carbide varistors in distribution arrester applications, some means must be provided to prevent the arrester housing from catastrophically rupturing upon varistor failure. When silicon carbide varistors are used within polemounted distribution protection applications, a gas-pressure release outlet can be provided in order to expel the hot ionized gases generated to the exterior of the arrester housing forming an external arc which causes the housing to fracture into a relatively few pieces.
Distribution arresters are employed on voltage distribution systems to protect the electrical equipment from overvoltage surges. Although the failure of distribution surge arresters is infrequent, it is possible that such failure can result in gas pressure buildup within the arrester housing. Subsequent rupture of the housing can cause damage to adjacent electrical equipment and personnel. The purpose of this invention is to provide an improved arrester that will rupture in a predetermined manner at lower internal pressures than previous designs to reduce the danger to equipment and personnel.